In the design of large buildings and similar structures, it is increasingly common to design and build large structures in the form of a plurality of independent but connected structural units. The individual structural units are separated by expansion joints, which enable one structural unit to have relative movement with respect to its neighboring unit or units, such as typically might be expected to result from thermal expansion and contraction, wind pressures, or even seismic disturbances. Typically, such expansion joints are provided with elastic seals to provide weather-tight integrity as well as to mask the open space between adjacent structural units.
A commercially acceptable and successful expansion joint seal must effectively combine both functional and aesthetic characteristics. Frequently, functional requirements can tend to be inconsistent with aesthetic requirements, leading the designers to incorporate various trade-offs and compromises.
The present invention is directed to specific improvements in expansion joint seals of a generally known type with the objective of improving the joint seal both functionally and aesthetically. Additionally, the invention is directed to an expansion joint construction having improved functional/aesthetic features which at the same time can be more economical to manufacture and install.
In representative prior art structures, such as, for example, reflected in the Riddle et al. U.S. Pat. No. 4,965,976 and/or the Rizza U.S. Pat. No. 4,781,003, it has been the practice to install at least portions of the seal-mounting hardware within the joint in order, among other reasons, to minimize the sight line of the joint seal. Even where portions of the mounting hardware are installed externally of the joint, as in the Riddle et al. U.S. Pat. No. 4,965,976, the external mounting hardware is at least partially projected into the space of the joint in order to minimize the exposed surfaces of the seal and thus minimize the exposed width or sight line of the seal. Historically, architects have been rather insistent with respect to minimizing the sight line of a joint, and this has dictated many compromises in the functional performance of the joint.
In accordance with the present invention, an expansion joint seal is provided which incorporates mounting hardware strips, which are installed on opposite sides of an expansion joint, but in manner to be entirely clear of the joint space. Additionally, the elastomeric seal, which is installed in the mounting hardware, is of a unique multi-part design. The multi-part seal includes a principal sealing member, which is secured at each side in the mounting hardware, spans the open space of the expansion joint, and constitutes the primary expansion joint seal. The mounting hardware includes means for separately mounting and retaining cover strips, which laterally abut the main sealing strip and form, in effect, lateral extensions thereof. The principal function of the cover strips is to provide a transition to the surfaces of the adjacent structural units, and to completely cover the edges of the mounting hardware.
By positioning the mounting hardware to be completely clear of the joint space, the overall width of the elastomeric seal may be wider than in a conventional seal construction, and this would normally be undesirable. However, in accordance with the present invention, the lateral cover strips can be of a different color than the primary sealing strip, so as to effectively mask the actual width of the sealing strip and give it the appearance of a much narrower strip.
An important functional advantage derived from the described arrangement is that, by eliminating mounting hardware from the interior of the joint, a much greater closing movement of the joint can be tolerated than with more conventional designs and/or the joint may be designed to be substantially narrower than is enabled with conventional installations. In addition, economies are realized in both the manufacture of the joint and in its installation. Because the seal is an assembly of three elements of two different designs, instead of a single wide sealing element, the extrusion die required is both simpler and smaller, and smaller extrusion equipment can be utilized in the production of the seal. Alternatively, the seal may be designed to much larger sizes than has been practical heretofore. Significant economies are also realized in the installation by reason of the greater ease of installing the mounting hardware on the outer surfaces of a structure, rather than within the joint. Particularly, where the joint is located at a corner, it is extremely difficult to install mounting hardware within the joint space. Moreover, where the opposed joint faces are irregular, conventional installation requires that the joint faces be re-worked and smoothed. This can be a difficult and expensive undertaking, which is completely avoided by the system of the invention.